Mike Crowley gets this basically right:
The Contract was really just a statement of a Republican vision that people did know about--a uniformity on taxes, national defense, "family values," regulations, and so on. In other words, the Contract was a manifestation of a familiar pre-existing Republican vision, not its first articulation. The problem for Democrats is that they don't actually have a similarly crisp and clear vision they can boil down into bullet points--at least not ones that aren't hopeless platitudes. At the moment, a Democratic contract would likely be an embarassingly worthless muddle (as was a little-noticed 2004 attempt at a party campaign platform). If Democrats can come up with a coherent vision then, fine, put out some kind of gimmicky document. But you can't put the cart before the horse.
Problem is, folks keep using the word "vision" when they mean "agenda." Go read the damn thing. Republicans didn't have a vision of a world with $500 child tax credits and "effective death penalty provisions", they had an agenda that included those items. Meanwhile, Democrats keep flailing about for 30 words worth of vision, when visions are, by definition, grand, sweeping articulations that encompass nearly all conceivable eventualities. You don't cram a vision into a handful of words, but you can condense an agenda into them. They just need to pick four things they want to achieve and talk only about those agenda items. The only question is, what should the four be?